Fleetwood Mac star Christine McVie says the group's hit record Rumours may not have been successful without the influence of drink and drugs.
The 1977 album, recorded during their turbulent years when their romantic relationships - mostly with each other - were falling apart, has been hailed as a masterpiece and sold more than 40million copies according to DailyMail.
Appearing on BBC Radio 4's Desert Island Discs today, host Kirsty Young asked McVie, 74, whether drugs 'had something to do with the brilliance of the music you were producing?'
Fleetwood Mac (L-R: John McVie, Mick Fleetwood, Bob Welch and Christine McVie) pose for a portrait under the Hollywood Sign 1974 in Los Angeles, California. Photo / Getty
McVie replied: 'That's something that we're never really going to know.'
The singer-songwriter and keyboard player revealed she penned Songbird, one of the band's most famous tracks, in the early hours of the morning, having taken cocaine and drunk champagne and been unable to sleep.
She said: 'I don't know if I would have written Songbird had I not had a couple of toots of cocaine and a half bottle of champagne and I just couldn't sleep, or written any of the songs that were on that album because I think we were all pretty loaded.
'I think I was probably the most restrained of the lot, but I was no angel.'
She added: 'There were a lot of drugs, everybody was making hash brownies.
'It was all very psychedelic if you wanted to go that way and somehow this music came out.'
The singer said the origins of Songbird are a 'mystery' to her, adding: 'It was as if I'd been channelled or something.
'The whole song, complete... came out within half an hour.
'This was at 3 o'clock in the morning and I couldn't go to sleep in case I forgot it.
'So, I had to play it (on the piano) all night long until I could get into the studio at about 9 o'clock the next day.
'I can't explain it. I wish all songs could come that easy. I just felt it was a universal kind of prayer or something. It's never happened to me since or before.'
She has since returned to Fleetwood Mac, writing songs again and says there is 'a great feeling of belonging' when she is with the band.
She added that the rockers are all 'clean, sober and happy' now.
'Somehow we crawled through the cracks, all five of us, all healthy, it's amazing,' she said.
Posed group portrait of Fleetwood Mac in September 1973. Left to right are Bob Weston, Christine McVie, Bob Welch, John McVie and Mick Fleetwood. Photo / Getty
McVie, who once bought a Rolls-Royce on a whim, also told how she retreated from the world, developing agoraphobia, after she quit the band and moved from California to Kent.
She said on the programme: 'I think I had some kind of wild image in my mind that I was going to be a country lady.'
When her second marriage fell apart she 'ended up in that big house on my own'.
She explained: 'I developed agoraphobia, a dreadful fear of leaving my front doorstep, I couldn't even get in my car, that's how bad it was.
McVie, who also wrote You Make Loving Fun, Oh Daddy and Little Lies, said that she barely touched the piano for many years because 'I wanted to write Songbird again, so was afraid to sit down and try'.
